1. Field of the Invention
The invention lies in the field of the pyrometallurgy of ferrous metals.
2. Description of the Prior Art
The increasing necessity of using low grade iron ores for making steel because of the depletion of high grade ores, and economic factors, have created a demand for reduction of the costs in producing steel from iron ore. Efforts to reduce costs have been directed to the elimination of the use of the highly fuel-consuming blast furnace. The present invention is directed to elimination of the use of the blast furnace by converting the iron oxide to the carbide followed by producing steel directly from the carbide in the basic oxygen furnace. The conversion of iron oxides to carbides for various purposes has received some attention in the past but there has been no known activity toward producing steel directly from the carbide in a basic oxygen furnace.
U.S. Pat. No. 2,780,537, the closest prior art known, discloses a process for converting iron oxides to carbides in a fluidized bed process in which carbon monoxide is used as the chief reducing and carburizing gas. The patent teaches that the reducing gas cannot contain hydrogen in an amount more than 50 percent by volume of the carbon monoxide content. It also refers to the prior art disclosing the use of hydrogen in a fluidized bed as a reducing gas for iron oxides having a low iron content. The reference alludes to use of the iron carbide product for making "metallic iron" and in an "iron production furnace" operating below the melting point of iron or steel, however, there is no teaching of use of the product for introduction into a fully molten steel system such as the basic oxygen furnace or electric furnace. Other somewhat remote prior art discloses processes for converting metallic iron to iron carbide rather than conversion of iron oxide to the carbide.
Still other prior art discloses fluid bed processes for the direct reduction of iron oxides to metallic iron which in turn could be further converted to carbide. However, these other direct reduction processes have the disadvantages that the product may be pyrophoric in some cases requiring briquetting, and stickiness is not completely eliminated in some processes so that difficulties arise with the fluid bed process.
It is an object of this invention to provide a process for making steel from iron oxide without the use of a blast furnace.
It is another object of this invention to provide a successful process for making steel from iron oxide by first converting the oxide to the carbide, followed by introducing the carbide directly into the basic oxygen furnace to produce steel.